Linear motor for a linear drive mechanism of a magnet levitation transport system

ABSTRACT

The invention relates to a linear motor for a linear drive mechanism of a magnetic levitation transport system. Said linear motor comprises a plurality of inductor supports ( 15 ) which are arranged in a row and which have grooves ( 14 ) crosswise to the longitudinal direction, said grooves being substantially equal distances apart from each other; and at least three linear motor lines ( 1, 2, 3 ), which are wound into windings ( 16 ) in a meandering shape and which are located in the grooves ( 14 ) in sections. Said coils ( 16 ) have winding heads ( 16.1, 16.2, 16.3 ) situated a distance (A) apart. The invention solves the technical problem of producing the windings continuously and economically by providing that the lengths (A′) of the winding heads ( 16.1′, 16.2′, 16.3′ ) of the of the at least three linear motor lines ( 1, 2, 3 ) are extended at a point of discontinuity ( 100 ) between two adjacent inductor supports ( 15 ).

[0001] The invention relates to a linear motor for a linear drivemechanism of a magnetic levitation transport system, with said linearmotor being comprised of a plurality of inductor supports which arearranged in a row and which have grooves crosswise to the longitudinaldirection, said grooves being substantially equal distances apart fromeach other, and at least three linear motor lines which are wound intowindings in a meandering shape and which are located in the grooves insections, with said windings having winding heads that are situated adistance (A) apart.

[0002] The three-phase alternate-current winding of a linear motorcomprises three linear motor lines laid like meanders that produce anelectromagnetic moving field. For example, linear motors are used todrive a magnetic levitation transport system for long-distance expresstraffic.

[0003] The production and laying of the alternate-current winding of alinear motor is accomplished with a laying vehicle that is put onto thetrack way (DE 3 37 719 A1).

[0004] The length of a winding period is defined by the groove/toothgeometry of the inductor packages and nearly constant over the length ofthe track way beam. But over the entire length of the track way theinductor cannot be fabricated and/or mounted as a uniform body or with auniform geometry, and moreover, fabrication tolerances do occur.Furthermore, the track way has interruptions which, for example, are dueto butt joints at bridge structures, for setoff of differences in lengthbetween inner track and outer track or due to elongation compensators(to compensate for changes in temperature).

[0005] It is possible to consider deviations from nominal sizes infabrication and laying of a winding, but only to such an extent as thesedeviations are exactly known from the very beginning on. Changes inlength occurring at a point of discontinuity throughout the service lifeof a motor winding due to thermal expansion and dynamic loads lead to anexpansion and compression load for winding heads in longitudinal trackway direction.

[0006] Some examples for potential impacts of such loads are givenbelow:

[0007] Adverse effect on functional stability with regard to operatingcurrent conductivity, operating and failure voltage strength andmechanical-geometric installation size accuracy.

[0008] Slight tolerances in length can be offset by the elasticproperties of the winding heads or line. For example, this would bepossible with ground level plate track ways having a length of up to 6m. With greater lengths, the tolerances in length add-up and the motorwinding cannot be fabricated continuously with a uniform size. Specialmeasures would have to be taken in the winding guidance. It has alsobeen contemplated to lay the motor winding with an expansion loop at apoint of discontinuity for thermal and/or dynamic elongation offset. Butit bears crucial disadvantages. Winding production is not possiblecontinuously. A standstill of the assembly machine will occur at everypoint of discontinuity for cutting of line length and for assembly ofline guidance. It entails more consumption of material (moving fieldline, clamps, fixing rails, etc.). In particular, a standstill of thelaying machine at every point of discontinuity is extremely obstructive.

[0009] The technical problem to be solved by the invention therefore isto propose a winding formation for a linear motor line at points ofdiscontinuity between inductor supports that evades the outlineddisadvantages and permits a continuous and low-cost winding production.

[0010] The technical problem outlined hereinabove is solved by a linearmotor having the features of claim 1 in such a manner that the lengthsA′ of the winding heads 16.1′, 16.2′, 16.3′ of at least three linearmotor lines are extended at a point of discontinuity between twoadjacent inductor supports. Further configurations are described in thesub-claims. The essential point of the invention lies in that thewinding heads of the meanders at the point of discontinuity are notshaped regularly but extended.

[0011] With the inventive shaping of the meanders at a point ofdiscontinuity, the length of the winding head is stretched inlongitudinal track way direction so that static deviations in length aremainly offset. The expansion and compression loads occurring with adynamic change in length of the expansion gap between two adjacent trackway beams moreover take effect upon an extended line section. Hence, theloads in total become smaller and can be absorbed by the elasticproperties of the winding heads.

[0012] There are several possibilities for executing the meanders withextended winding heads. In a preferred manner, the lengths of theextended winding heads of at least three linear motor lines are extendedby a mainly equal extent. It is thus ensured that after bridging thepoint of discontinuity, the at least three linear motor lines are againarranged in the same phase arrangement.

[0013] Furthermore, it is proposed that for simplifying the productionof extended winding heads these shall be extended in pre-definedintervals depending on the length of the point of discontinuity to beoffset. It means that the lengths of the winding heads are extended byan allocated pre-defined amount if the length difference to be offsetlies within a pre-defined interval. Thus the differences in length areadequately compensated, without calling for absorption of too greatmechanical stresses in the winding heads, while the production ofextended winding heads is simplified in such a manner that the devicefor producing the extended winding heads must be arranged only forpre-defined differences in length.

[0014] It is furthermore purposive to configure adjacent winding headsof three phases jointly at one side of the inductor support. For ease ofaccessibility, it is proposed to configure the extended winding heads onthe outer side of the inductor support, i.e. not at the track way innerside.

[0015] Thus the winding can be fabricated and laid continuously over theentire linear motor section, without causing any interruptions. Inanother patent application filed at the same time it is proposed tomeasure the groove/tooth geometry during the production of the meanderwindings by way of a measuring device in situ and to shape the meandersexactly in conformity with the measured groove/tooth geometry. With theinvention presented here, it will then be easy to approach and measurepoints of discontinuity with the measuring facility and to shape and laythe “extended” meander configuration individually, accurately fitting,and at the exact location in fully automatic mode according to thisinvention.

[0016] During their service life, the extended winding heads inconformity with the invention may lose their form stability due topermanently changing loads (expansion and compression), and sink down.Hence, the winding heads might protrude out of the free space which iscreated by the encroachment of the rider of the magnetic levitationvehicle. Winding heads protruding beyond the free space would be touchedduring passage with a magnetic levitation vehicle and could be damaged.

[0017] The winding heads should therefore be fixed. Consequently, to fixthe position of extended winding heads at a point of discontinuity, itis proposed to install additional fixing elements such as retainer beltsor plates at the track way beam. But these are relatively costly.

[0018] Another embodiment of the invention lies in proposing a simpleand low-cost additional holder for the winding heads at points ofdiscontinuity, integrating non-occupied grooves. For this purpose, itshould be possible to insert retainer means into non-occupied grooveswhich fix the winding heads or on which the winding heads may rest.

[0019] To this effect it is proposed to captivate at least oneprefabricated rigid bar in one or several stator grooves that are notoccupied by the winding, thus allowing the extended winding heads torest on said rigid bar. These assembly services could be performedimmediately after the production of the winding.

[0020] An example for an embodiment of the invention is illustrated onthe attached drawing, where

[0021]FIG. 1 shows a view under the track way with a discontinuity point

[0022]FIG. 2 shows a side view of the same position

[0023]FIG. 3 shows a section through the side view, and

[0024]FIG. 4 shows a detail at the retainer bar.

[0025] Shown in FIGS. 1 and 2 is the course of the winding of the linearmotor lines 1, 2, 3 at one point of the butt joint or of an expansiongap between two inductor supports 15. One expansion gap forms thediscontinuity point 100. Upstream and downstream of the discontinuitypoint 100, the stator grooves 14 are densely occupied withmeander-shaped windings 16. One winding period or one winding head 16.1,16.2 and 16.3 has the length A.

[0026] Especially visible on FIG. 2 are the crimpings of the meanders.The crimpings are required because the winding heads 16.1, 16.2 and 16.3cross each other. By laying the winding heads 16.1, 16.2, and 16.3 aboveeach other, it is possible to fill the existing space optimally.

[0027] At the discontinuity point, the winding heads 16.1′, 16.2′, and16.3′ on the track way outside (reference 11 track way center) areextended in accordance with the invention, receiving the period lengthA′ by way of the proposed measure. The period length A′ roughlycorresponds to the threefold of the period length A which in turncorresponds to the threefold of the distances of grooves 14 to eachother. By configuring the period length A′ as a multiple of the periodlength A, it is achieved that the spatial phase distribution along thetrack way is by and large undisturbed, despite the discontinuity point100. As a matter of fact, it depends upon the width of the discontinuitypoint 100 how exactly the multiple of period length A can be compliedwith. In any case, however, by way of a smart choice of grooves 14downstream of discontinuity point 100, it can be achieved that thedeviation of period length A′ from a multiple of period length A issmaller than the distance between two grooves 14.

[0028] As has been described before, FIG. 1 shows that the extendedwinding heads 16.1′, 16.2′, and 16.3′ of the linear motor lines 1, 2,and 3 are situated on that side of the inductor support 15 which facesthe outside of the track way. The accessibility of the extended windingheads 16.1′, 16.2′, and 16.3′ is thereby simplified. A relatively largedistance between consecutive windings of each of the linear motor lines1, 2 and 3 is put up with. Conversely, it is also possible, for example,to occupy all grooves with windings and to extend the extended windingheads either on one or on the other side of the inductor supports. Thenit is merely required to extend the winding heads by the length of thediscontinuity point 100. Downstream of the discontinuity point 100, thewindings 16 of the linear motor lines 1, 2, and 3 can be then bearranged in the hitherto applied sequence. If the discontinuity point100 just represents a small gap, a nearly steady transition of theelectromagnetic moving field generated by the linear motor lines 1, 2,and 3 is achieved.

[0029] As some grooves 14 remain empty near the discontinuity point 100on FIG. 1, at least one of the non-occupied grooves can accommodate aretainer element 40 which serves for supporting the extended and crimpedwinding heads 16.1′, 16.2′, and 16.3′.

[0030]FIG. 3 shows a magnified view of the section B-B through thearrangement in FIG. 2. The winding heads 16.1′, 16.2′, 16.3′ lye in afree space 12 which is formed outwardly (S) by the lateral guide railand downwardly (U) by the rider of the magnetic levitation transportvehicle. Inserted into one of the grooves 14 of the inductor package 15from the inductor outside is a cylindrical retainer bar 40, supportingthe lower winding head 16.1′. FIG. 3 shows that the two other windingheads 16.2′ and 16.3′ rest on the lower winding head. Any other form offixing or supporting of winding heads to achieve the intended purpose isalso feasible.

[0031] The retainer bar 40 is provided as a fitting made of epoxy resinand is captivated in stator groove 14. At its end and roughly in itscenter, the retainer bar 40 carries two collars 43 and 44 at a distance,which is slightly bigger than the groove length. The distance betweenthe two collars 43 and 44 is properly rated to ensure a precise and safeinstallation position. The width 49 of the collars is smaller than thediameter of groove 14. When slid-in, the collars 43, 44 are in aposition pointing downwardly (to the grove outlet side). Afterinsertion, the retainer bar is turned by approx. 180° C. During thisprocedure, the collars 43 and 44 turn from the groove opening to thegroove subground. In its longitudinal direction, collars 43 and 44 fixthe retainer bar 40. At the outside of the inductor, a grounding line 10is fixed in a spring channel 50. The function and meaning of a groundingline was extensively disclosed in the German patent DE 196 20 222.1 C1.

[0032]FIG. 4 shows the detail of collar 44 at retainer bar 40. The width49 of collar 44 is smaller than the diameter 45 of the retainer bar. Thecollar 44 is chamfered 47 so that, when twisted, it engages due to itselastic ductility in the final position downstream of the spring channel50 (FIG. 3), thus preventing it from being turned-back.

1. A linear motor for a linear drive mechanism of a magnetic levitationtransport system, with said linear motor being comprised of a pluralityof inductor supports (15) which are arranged in a row and which havegrooves (14) crosswise to the longitudinal direction, said grooves beingsubstantially equal distances apart from each other, and at least threelinear motor lines (1, 2, 3) which are wound into windings (16) in ameandering shape and which are located in the grooves (14) in sections,with said windings (16) having winding heads (16.1, 16.2, 16.3) that aresituated a distance (A) apart, characterized in that the lengths (A′) ofthe winding heads (16.1′, 16.2′, 16.3′) of the at least three linearmotor lines (1, 2, 3) are extended at discontinuity point (100) betweentwo adjacent inductor supports (15).
 2. A linear motor pursuant to claim1, characterized in that the lengths (A ) of the winding heads (16.1′,16.2′, 16.3′) of the at least three linear motor lines (1, 2, 3) areextended by a mainly equal amount.
 3. A linear motor pursuant to claim 1or 2, characterized in that the lengths (A′) of the winding heads(16.1′, 16.2′, 16.3′) are extended in pre-defined intervals, dependingupon the length of the discontinuity point (100) to be offset.
 4. Alinear motor pursuant to any one of claims 1 to 3, characterized in thatthe lengths (A′) of the winding heads (16.1′, 16.2′, 16.3′) mainlycorrespond to a multiple of the distances (A).
 5. A linear motorpursuant to any one of claims 1 to 4, characterized in that the extendedwinding heads (16.1′, 16.2′, 16.3′) are situated on the same side of theinductor supports (15).
 6. A linear motor pursuant to claim 5,characterized in that the extended winding heads (16.1′, 16.2′, 16.3′)are situated on the side of inductor supports (15) that faces theoutside of the track way.
 7. A linear motor pursuant to any one ofclaims 1 to 6, characterized in that a retainer element (40) forextended winding heads (16.1′, 16.2′, 16.3′) is laid into at least oneof a groove (14) of an inductor support (15) which is not occupied by awinding (16).
 8. A linear motor pursuant to claim 7, characterized inthat the retainer element (40) is captivated.
 9. A linear motor pursuantto claim 7 or claim 8, characterized in that the retainer element is acylindrical retainer bar (40).
 10. A linear motor pursuant to any one ofclaims 7 to 9, characterized in that the retainer element (40) is of anon metallic configuration.